Intramuscular Hydatid Cyst of the Thigh: A Rare Presentation in an Elderly Patient.

Intramuscular hydatid cysts are an uncommon presentation of echinococcosis, with most cases occurring in the liver and lungs. This case report describes an 81-year-old male who presented with a painless, progressively enlarging swelling in the right thigh noticed over the past year. The patient's history included trauma to the area from an animal-related incident five years earlier. Physical examination revealed a firm, irregular, and non-tender mass. Ultrasonography suggested a multiloculated cystic lesion with calcification, raising suspicions of a hematoma or hydatid cyst. Fine-needle aspiration cytology indicated an organized hematoma with secondary calcification. Given the diagnostic uncertainty, surgical excision revealed a 3x3 cm hydatid cyst in the intramuscular plane. A histopathological examination confirmed the diagnosis. The patient's postoperative course was uneventful, with no signs of recurrence at the three-month follow-up. This case underscores the importance of considering hydatid disease in the differential diagnosis of intramuscular swellings, particularly in patients with relevant exposure histories.